Bullard, a voting member of the bank's influential Federal Open Market Committee, said the Fed should continue with its bond-purchasing program because it's still the best way to stimulate the sluggish economic growth. "Quantitative easing is closest to standard monetary policy, involves clear action and has been effective," Bullard said.

"You're going to hear Ben Bernanke speak tomorrow," said Michael Bapis, managing director at HighTower's The Bapis Group. "I don't think he's going to provide numbers, but when will they begin tapering -- what would prompt them to raise the pace of QE beyond $85 billion?"

Markets were bolstered by Home Depot which raised its sales outlook for 2013. Elsewhere, shareholders voted down a proposal to force JPMorgan Chase to split the roles of chief executive and chairman, currently held by Jamie Dimon. Some investors have complained that Dimon wields too much authority at the country's largest bank.

"Investors are less fearful that economic growth may be too slow," Ed Yardeni, New York-based chief investment strategist at Yardeni Research, wrote in a note. "They seem to be less concerned about the 'stall speed' scenario, in which slow growth morphs into negative growth, i.e., a recession," "So they are less fazed about the phasing out of QE."

JPMorgan Chase shares popped 1.4% to $53.02 after a proposal to split Jamie Dimon's dual roles as CEO and chairman failed during the company's annual meeting on Tuesday. Press reports had suggested Dimon could quit if the vote had gone against him.

Home Depot gained 2.5% to $78.71 after posting first-quarter earnings that beat expectations by 6 cents at 83 cents a share, as revenue also topped forecasts. The company hiked its full-year earnings and sales outlook. "We continue to see benefit from a recovering housing market that drove a stronger-than-expected start to the year for our business," CEO Frank Blake said in a statement.

Medtronic jumped 4.9% to $52.35 as the biggest gaining stock in the S&P 500 after the medical device maker produced fiscal-fourth quarter profit that exceeded Wall Street's target by seven cents at $1.10 a share, with revenue beating estimates as well. Sales growth in the endovascular and structural heart units were especially robust during the quarter.

Carnival plunged 4.3% to $33.81 as the biggest loser in the S&P after the cruise line operator slashed its full-year earnings guidance to $1.45 to $1.65 a share, below the average analyst estimate of $1.98. The company is trying to lure in customers with cheaper prices as it continues to suffer the effects of high-profile incidents at its cruise ships.